Chronic Inflammation and Its Causes

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Questions and Answers

What is the primary function of major protein (MBP) found in eosinophil granules?

Regulates blood flow in tissues

Stimulates macrophage activation

Increases antibody production

Is toxic to parasites (correct)

What characterizes granulomatous inflammation?

Collections of activated macrophages and T lymphocytes (correct)

Presence of large fluid-filled cavities

Rapid healing with minimal tissue damage

Massive neutrophil infiltration

What role do mast cells play in allergic reactions?

Release mediators such as histamine and prostaglandins (correct)

Act as phagocytes to destroy allergens

Produce antibodies against pathogens

Enhance the function of eosinophils

Which type of cells are associated with the formation of multinucleated giant cells in granulomatous inflammation?

Activated macrophages Signup and view all the answers

What can result from the strong activation of T lymphocytes?

Macrophage activation that may injure normal tissues Signup and view all the answers

What is one likely outcome of acute inflammation?

Abscess formation Signup and view all the answers

Which condition is an example of chronic inflammation?

Hepatitis Signup and view all the answers

What type of microorganisms often lead to persistent infections causing chronic inflammation?

Mycobacteria and certain viruses Signup and view all the answers

Which characteristic is typically observed in chronic inflammation?

Infiltration with mononuclear cells Signup and view all the answers

What is a common cause of chronic inflammation related to the immune system?

Hypersensitivity diseases Signup and view all the answers

What is the term used to describe the healing process in chronic inflammation?

Angiogenesis Signup and view all the answers

What can induce tissue destruction in chronic inflammation?

Products from inflammatory cells Signup and view all the answers

What is a feature that distinguishes chronic inflammation from acute inflammation?

Coexistence of inflammation and tissue injury Signup and view all the answers

What characterizes chronic inflammation in the lung?

Destruction of parenchyma replaced by connective tissue Signup and view all the answers

Which type of cell is considered the dominant cell in chronic inflammation?

Macrophages Signup and view all the answers

What is the function of macrophages in chronic inflammation?

Phagocytosis and initiation of tissue repair Signup and view all the answers

Which type of lymphocyte predominantly drives inflammation in autoimmune diseases?

CD4+ T lymphocytes Signup and view all the answers

Which type of T lymphocyte is involved in the defense against helminthic parasites?

TH2 cells Signup and view all the answers

What role do eosinophils play in immune reactions?

Mediating reactions through IgE and parasitic infections Signup and view all the answers

What mediator does macrophages secrete to promote inflammation?

TNF-a and IL-1 Signup and view all the answers

What histological feature is associated with acute bronchopneumonia?

Neutrophils filling alveolar spaces Signup and view all the answers

What is the primary role of granuloma in the body?

Serves as a defense mechanism Signup and view all the answers

Which type of granuloma is caused by persistent T cell-mediated immune response?

Immune granuloma Signup and view all the answers

What is the appearance of caseous necrosis in granulomas?

Granular and cheesy Signup and view all the answers

Which disease is characterized by caseating granulomas and Langhan's giant cells?

Tuberculosis Signup and view all the answers

What type of granulomas do Crohn disease and sarcoidosis typically involve?

Non-caseating granulomas Signup and view all the answers

What is a common feature of foreign body granulomas?

Induced by inert foreign materials Signup and view all the answers

How does acute inflammation differ from chronic inflammation in terms of response time?

Acute inflammation is immediate and rapid Signup and view all the answers

What type of granulomas are typically formed as a reaction to talc powder?

Foreign body granulomas Signup and view all the answers

Study Notes

Chronic Inflammation: Granulomatous Inflammation

Chronic inflammation is a prolonged response (weeks or months) where inflammation, tissue injury, and repair attempts coexist.
Acute inflammation outcomes include:
- Complete resolution with native cell regeneration, restoring the site to normal.
- Abscess formation, typically due to pyogenic organisms.
- Healing by connective tissue replacement (fibrosis and scarring) occurring after extensive tissue destruction in non-regenerating tissues or with abundant fibrin exudation.
- Progression to chronic inflammation.

Chronic Inflammatory Conditions

Chronic inflammation encompasses various conditions like:
- Hepatitis
- Chronic cystitis
- Inflammatory bowel disease
- Chronic cholecystitis
- Pancreatitis
- Barrett esophagus
- Gastritis
- Osteomyelitis
- Sialadenitis

Causes of Chronic Inflammation

Persistent infections: difficult-to-eradicate microorganisms (e.g., mycobacteria, certain viruses, fungi, parasites) often triggering delayed-type hypersensitivity, sometimes manifesting as granulomatous reactions; unresolved acute inflammation can also evolve into chronic inflammation.
Hypersensitivity diseases (autoimmune): immune responses against self-tissue.
Prolonged exposure to potentially toxic agents:
- Toxic exogenous substances (e.g., silica, asbestos leading to conditions like silicosis and asbestosis)
- Toxic endogenous substances (e.g., cholesterol-induced atherosclerosis).

Morphologic Features of Chronic Inflammation

Infiltration with mononuclear cells (macrophages, lymphocytes, plasma cells).
Tissue destruction or necrosis, often resulting from persistent offending agents and inflammatory cell products.
Attempts at healing (repair): connective tissue replacement of damaged tissue through new vessel proliferation (angiogenesis) or fibrosis.

Chronic vs Acute Inflammation in Lung

Chronic inflammation in the lung shows characteristic features like collections of chronic inflammatory cells, parenchyma destruction, replacement by connective tissue, and fibrosis.
Acute inflammation, in contrast, demonstrates neutrophils filling the alveolar spaces and congested blood vessels.

Cells and Mediators of Chronic Inflammation

Macrophages: dominant cells in chronic inflammation, characterized by phagocytosis, tissue repair initiation, inflammatory mediator secretion (e.g., TNF-α, IL-1, chemokines), antigen presentation to T lymphocytes, and responsiveness to T lymphocyte signals.
Lymphocytes: key drivers in autoimmune and chronic inflammatory diseases, including B and T lymphocytes. B cells differentiate into plasma cells which produce antibodies, and T cells (especially CD4+ T cells) release cytokines impacting the nature of the inflammatory response. TH1, TH2, TH17 subtypes have different roles (e.g., TH1 in bacterial/viral defense, TH2 in helminthic parasites, and allergic responses).
Eosinophils: abundant in IgE-mediated and parasitic infections; release eotaxin (attracting eosinophils), major basic protein (toxic to parasites), and contribute to tissue damage in allergic reactions.
Plasma cells: terminally differentiated B lymphocytes producing antibodies against persistent foreign antigens or altered tissue components within the inflammatory site.
Mast cells: widely distributed in connective tissue, involved in both acute and chronic inflammation by degranulating and releasing mediators like histamine and prostaglandins, triggering responses like allergic reactions (potentially severe).

Granulomatous Inflammation

A form of chronic inflammation marked by collections of activated macrophages, frequently with T lymphocytes and sometimes necrosis (granulomas).
Granuloma formation aims to contain difficult-to-eradicate pathogens.
Strong T-lymphocyte activation can trigger macrophage activation, potentially causing injuries to normal tissues.

Morphology of Granuloma

Activated macrophages, now called epithelioid cells, display pink granular cytoplasm with indistinct boundaries.
Surrounded by cuffs of lymphocytes, older granulomas sometimes show a rim of fibroblasts.
Fusion of macrophages forms multinucleated giant cells (40-50 µm diameter) with a large cytoplasm and multiple nuclei, occasionally with central necrosis.
Granulomas effectively wall off infectious agents, serving as a defense mechanism.

Types of Granulomas

Immune granulomas: arise due to persistent T-cell mediated responses, often in response to microbes (e.g., Mycobacterium tuberculosis).
Foreign body granulomas: induced by relatively inert foreign bodies (e.g., talc, sutures) too large for phagocytosis.

Morphology of Granuloma (specific to Tuberculosis)

Granulomas associated with tuberculosis (and similar microbes) exhibit central necrosis (caseous necrosis).
Gross appearance is often granular and cheesy.
Microscopy shows eosinophilic amorphous, structureless, granular debris, losing cellular details.

Morphology of Granuloma (specific to Crohn's, Sarcoidosis, foreign body reactions)

Granulomas associated with Crohn's disease, sarcoidosis, and foreign body reactions are non-caseating, lacking a necrotic center.

Examples of Diseases with Granulomatous Inflammation

Tuberculosis: caseating granuloma, Langhan's giant cells.
Syphilis: gummas (granulomas), plasma cells.
Leprosy: non-caseating, acid-fast bacilli present.
Cat scratch disease: rounded or stellate granulomas, with neutrophils.
Sarcoidosis: non-caseating granulomas
Crohn's disease: non-caseating granulomas, dense inflammatory infiltrate.

Foreign Body Granuloma (Nonimmune)

Granulomatous reaction surrounding suture materials and talc, respectively.

Differences Between Acute and Chronic Inflammation

Response: Acute inflammation is an immediate reaction to tissue injury, while chronic inflammation is a persistent reaction.
Onset/Duration: Acute inflammation is rapid (hours to weeks), whereas chronic inflammation is slow (weeks to months/years).
Immunity: innate in acute, cell-mediated in chronic.
Predominant Cell Type/Cellular Infiltrate: acute is primarily neutrophils; chronic is mostly lymphocytes, macrophages, and monocytes.
Tissue Injury/Fibrosis: acute usually mild and self-limiting; chronic often severe and progressive.
Local & Systemic Signs: acute often pronounced; chronic less prominent.
Outcome: acute inflammation outcomes include resolution, abscess formation, or progression to chronic inflammation; chronic leads to tissue destruction, fibrosis, and necrosis.

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Description

This quiz explores the complex nature of chronic inflammation, including its definition, outcomes, and various chronic inflammatory conditions such as hepatitis and inflammatory bowel disease. Additionally, it delves into the causes that lead to prolonged inflammatory responses. Test your understanding of these crucial aspects of chronic inflammation!